Non-sequential expression of multiple immunoglobulin classes by isolated B-cell clones

As humoral immunity to a given antigen is generally thought to display an early IgM response which is later dominated by IgG synthesis, it has long been thought that clones of antibody-producing cells switched from μ to γ (refs 1-5). The sequence of appearance of immunoglobulin classes produced by the progeny of isolated precursors (B cells) to antibody-forming cells may answer the questions (1) does a clone of cells switch from μ to γ to α, and (2) do all clones switch in the same order following antigen stimulation? Results presented here show that there is no order of expression of immunoglobulin class with time by B-cell clones stimulated by antigen in the presence of carrier help, because any class can appear first or simultaneously with any other class.